The GI-7B(t) is a very rugged metal ceramic tube built during the cold war for use on Russian tanks and other military vehicles. The GI-7BT is a more ruggedized version of the same tube featuring a fatter ceramic element but otherwise the same as the thinner GI-7B. You will find these tubes that have white ceramic and some that have pink or purple ceramic and we have found no difference in the performance of these tubes. NOTE: Some suppliers sell the GI-70B and the GI-70BT tube which is the same tube WITHOUT the anode cooler. Always be aware of what you are buying.

Dentron Clipperton L and Clipperton QRO
Notes: The Clipperton L and the Clipperton QRO are both a beautiful table top near legal limit amplifier and will perform to full specifications when properly retrofitted with the GI-7B tubes. They are easier to retrofit than the MLA-2500 and will give nearly identical performance. Please read all the notes below on the MLA-2500 before you decide to start this project.

Dentron GLA-1000
Notes: The GLA-1000 is a beautiful little amplifier and will perform to full specifications when properly retrofitted with the GI-7B tube. It is important to note that, as with any retrofit, you should NOT expect more out of this amplifier than it was designed to provide. You can not get more power output from this amp than the power supply is capable of providing. Also, the retrofit of the GLA-1000 (this applies to most of the other sweep tube amp retrofits too) requires changing the power supply to a voltage doubler. When you do this, the plate voltage will be higher. Obviously if you can not get more power from the power supply, then the plate current will be lower. What this means is that the plate load impedance is going to change. What that means is that the Pi-network will no longer provide a proper match to the antenna jack. You can get the amp to work but it will not come up to full output. I have provided some general guidelines for establishing the proper tap points on a tank coil here http://gs35b.com/discussion.html. There are other opinions on this subject so please understand this is just one of them. I am not in a position to hold your hand through a project like this so be well aware of what you are getting yourself into before taking this on. W4ZT

Dentron MLA-2500
Notes: The MLA-2500 is a beautiful table top near legal limit amplifier and will perform to full specifications when properly retrofitted with the GI-7B tubes... BUT... this is NOT a project for the faint of heart. If you do not have experience doing metal work, schematic reading, figuring things out from pictures, troubleshooting and intuitive layout design based on available components, you may not want to take this project on. You are not going to find a list of detailed instructions here for doing this retrofit. You are not going to find a detailed list of parts for doing this retrofit. You will find a detailed schematic that reflects most of the changes that can be made but not necessarily all of them. If you do not find the information you are looking for here, I am afraid that I do not have it. Carefully study the pictures in these retrofits. You should also study other MLA-2500 retrofits done using other tubes. All of this study will give you better ideas for doing your own work. W4ZT

Please note: Although we show you how the GI-7B can be used to retrofit the SB-230 in the original conduction cooled configuration, we feel it is only fair to tell you that the tube will not cool as well as a conduction cooled amp as it will with the factory cooler on the tube and a small fan blowing on it. If you still want to do the conduction cooled retrofit, we can supply the new cooler as well as the socket. Even if you do the retrofit as a conduction cooled amp, it is wise to blow a small amount of air around the tube to keep the base of the tube properly cooled. It is also worth mentioning that even though the SB-230 has been retrofit with the GI-7B standing vertical, that is not the best or recommended way of doing it. Our experience indicates that there is much less work and much better operation if the tube is mounted horizontally against the right side wall. We do have sockets and can provide the cooler for the conduction retrofit but We do NOT provide complete KITS for this retrofit.

GI-7B Tubes - I have many people ask about these tubes and where to buy them. You can purchase them from any number of dealers, most of which are outside the USA. The prices listed by these dealers usually does NOT include the shipping charge so be sure to check that before ordering. Also, be sure that the price includes the anode cooler. You don't want to pay full price for a tube that doesn't have the anode cooler. The GI-70 does NOT have a cooler.

These sockets are professionally crafted by K4POZ and W4ZT to provide you the best socket for your retrofit or new construction project. These sockets are designed for the best possible connections to the tube while allowing full air flow around the socket for more than adequate tube cooling. These are PLUG IN sockets. There are NO hold down clamps to fiddle with. The tube is completely removable and insertable from the anode side of the chassis. We have designed the grid and cathode connections using full contact finger stock to insure that you have the best RF connection possible. The socket can be mounted either on top of a chassis or sub mounted below a chassis which is pressurized for forced air cooling. Mounting can be horizontal or vertical. Please COMPARE this socket with any other socket you can find.

(click on the small pictures to see larger pictures in a new browser window)

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View straight down into the socket showing the finger stock.

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The socket can be mounted below the chassis by reversing the mounting hardware.

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Socket shown mounted below the chassis.

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Tube in the socket mounted below the chassis.

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PTFE Chimney
No longer available.

Comments from users:

What a nice piece of hand-work!
I thank your for your UFB and kind communication and support... IT9BLB/KF6FBC

The GI-7B socket arrived today. I was amazed at the high quality.
This is much better than the other one I bought, and better than any that I have seen... Your socket is very well built, compact and provides much better contact to the tube than the others. The socket will be ideal for all of my GLA-1000B conversions... K8KSW

That's a nice piece of work. I wont build them myself anymore, I'll use yours!... W4EMF